A virus for mass destruction of cutworms
By SBJamias
January 2005 UPLB HORIZON Vol.7, No.1 

Development workers attest that if a technology was developed for and with a farmer, it will be easily adopted and diffused throughout the community. And within the community emerges a farmer-leader, who by his natural curiosity, innate knowledge (we term indigenous technical knowledge), progressive thinking, experience, and daring, can help transform a village. Such is the case of 62-year-old Ka Modesto Gabriel, a hard-working and successful rice-eggplant farmer in Barangay Bantug, a farming village in Asingan, Pangasinan.

Tagged as the 'eggplant country', Asingan used to produce the biggest and the best eggplants. Pangasinan produces about 31 percent of the country's yearly harvest of more than 180,000 metric tons of eggplant-the most popular vegetable in the Filipino diet.

Ka Modesto wielded political clout and social influence in the village as a 'perennial' chairman of the 150-strong Bantug Samahang Nayon Multi-Purpose Cooperative (BSNMPC). Thanks to his rallying efforts in 2000, researchers of the National Crop Protection Center (NCPC), led by project leader Mr. Mario Navasero, easily taught the villagers how to monitor the pest populations in their farms as basis for an Integrated Pest Management (IPM) system for eggplant.

But even progressive-minded farmers can have stubborn moments. That same year, Mr. Navasero broached to Ka Modesto the use of biopesticide, Spodoptera litura Nuclear Polyhedrosis virus (SINPV), to control cutworms. This was meant to reduce or even cut his costly spraying of chemical insecticides two times a week just to produce a marketable yield. Many other farmers sprayed a mixture or 'cocktail' of chemical pesticides everyday! Ka Modesto was lukewarm about the technology.

It took another two years for the patient and equally zealous Mr. Navasero to re-introduce the technology. And nature itself intervened to demonstrate its merit.

From Nov. 2002 to March 2003, armies of cutworm (Spodoptera litura) ferociously attacked Ka Modesto's eggplants. And not just once, but twice - despite his chemical sprays! The cutworms first feasted on the leaves, shoots and stems of his eggplants at their late vegetative stage. Then, they devoured the flowers and setting fruits of the surviving plants near harvest time. Alarmed, Ka Modesto began picking out the worms mano-mano (by hand) as advised by Mr. Navasero. But soon, this became very tedious, especially under the overlapping canopies of 1,300 eggplants in a 1,000-square meter farm. Desperately losing the cutworm battle, his fellow farmers abandoned their fields.

As if on cue ('providential,' stresses Mr. Navasero), a Spodoptera litura NP virus broke out in Ka Modesto's farm. Miraculously, the dreaded cutworms began dying before his eyes until their population dropped - without chemical spray. Mr. Navasero pointed out that it was a 'virus' that killed the overcrowded cutworms.

"The outbreak is a natural phenomenon when the cutworm population rises so high. Like the common cold, the virus spreads faster in a crowded place, thus infecting healthy cutworms." What amazed the farmer more is that by the wonders of science, he can actually produce the virus-from the dead bodies of infected cutworms!

Convinced and humbled, Ka Modesto began learning from Mr. Navasero how to produce and use SINPV. One week after he sprayed the diluted mixture on his 13-week-old eggplants, the destructive cutworm turned sluggish, their greenish brown skins faded to a murky or gray brown, and they did not feed. After about two to three days, they died.

Invigorated, Ka Modesto began producing SINPV for his next cropping. He also experimented a lot. For instance, he was able to produce the virus from healthy cutworms grown from gabi, which he fed with eggplant leaves dipped in SINPV suspension. Some farmers who observed his cut-worm free field also began collecting infected cutworms for their own use and asked him to teach them.

Realizing the potential of turning production of the virus into a livelihood project in the village, Ka Modesto requested Mr. Navasero to train the cooperative members on how to produce, use and store SINPV. To him, "SINPV was a simple and 'doable' technology that I wanted to share with my fellow farmers."

Hence, "although it was not part of the NCPC project, nor did it have funding, I seized that opportunity to share this useful and relevant technology in the village," Mr. Navasero recalls. "It was my conviction and commitment as a scientist to give farmers a cheap, safe and environment-friendly alternative, thus empowering them to help revive their eggplant industry."

How the virus kills
"SINPV specifically targets cutworms and kills them by becoming parasites inside their bodies. Hence, the worm must first ingest the virus by feeding on contaminated leaves or plant parts," Mr. Navasero explains. "Scientists have known SINPV to be a biopesticide, and developed countries have even marketed it as Spod-X and Spodo-lure, as wettable powder or liquid concentrate, but testing in the country has been limited to laboratories and small areas," he points out.

"The virus attacks and rearranges the very cell structure of the caterpillar, forming 'crystals' which are, basically, inanimate and incapable of maintaining life," he explains. "Infected caterpillars excrete these crystalline structures through their droppings or regurgitated fluids as a sign of stress. When another caterpillar eats anything these crystals are on, the virus will multiply in all its internal organs and tissues, eventually killing it," he adds.

"Since the digestive tract of the caterpillar is alkaline, it breaks down the crystals, releasing the now-active virus." However, he assures that the virus is safe to humans, including other mammals, birds, fishes and non-target insects because these are acid-based, and thus, cannot mass produce the virus.

Why is a virus more effective than chemical spray? "Cutworms are hardy, plentiful and stealthy. It is hard to spray on worms that have a lot of host plants, thus can thrive anywhere, and which feed voraciously at night on young or newly germinating plants (thus, defenseless) then ride curled under the soil at daytime," explains Mr. Navasero.

How to produce the virus

To produce his first SINPV, Ka Modesto gathered moribund and dead larvae that were still firm and would not rupture when touched using a wooden stick. He collected the ruptured and dead larvae that were too soft by clipping-off the portion of the leaf containing them into a receptacle. He then macerated the collected materials using a stick to squeeze out the liquefied contents. He added about 30 to 50 ml of water and stirred the mixture for a few minutes.

He then transferred the SINPV suspension into screw-capped bottles and stored these in the freezer of an ordinary refrigerator to prevent spoilage and to prolong the viability of the virus.

To use a spray, Ka Modesto mixed 10 to 15 larval bodies for every 16L capacity knapsack-sprayer. He labeled each bottle containing the brownish and foul-smelling liquid with their concentration (e.g. number of worms). Since the SINPV is quite sensitive to sunlight, he sprayed in the late afternoon, making sure to wet the surfaces of his eggplant leaves uniformly. One week after spraying, many cutworms died and their population continued to crop even without chemical spray.

Spreading the 'virus technology'

To train about 70 other cooperative members challenged Mr. Navasero's resourcefulness and strategizing abilities. First, he and his entomologist-wife, Marcela of the Plant Pest Clinic, Department of Plant Pathology, rendered their training services for free,

From Oct. to Nov. 2003, the couple scheduled their 'staggered' training schedules once a week to coincide with Mr. Navasero's visit to Barangay Bantug for his project with CropLife Philippines, Inc. The 'ride-on' free transport was generously supported by the company's Executive Director, Mr. Simeon Cuyson.

To reach more farmers, they also trained potential trainors first, namely, Ms. Crisanta Taganas and Ma. Luisa Jamias, the manager and the assistant manager of the cooperative, respectively. Thus, activities and production were sustained even the experts were not in the area.

Further, to ensure that farmers would have enough host plants and cutworms for rearing the couple provided free mulberry cuttings while Ka Modesto offered his gabi plants. The farmers planted soybean a month before the training started. Mrs. Navasero also developed a technique of rearing cutworms on soybean that facilitated mass production in the laboratory. The farmers provided the rearing cages, some facilities and rearing media, and became responsible for their safekeeping in the cooperative.

Because of the community's collective efforts, the BSNMPC members are now mass producing and using SINPV as a biopesticide in Narangay Bantug. "They have also improvised methods to produce more SINPV with least cost, with host plants available in their locality, and with their existing resources," smiles Mrs. Navasero.

From being producers, the farmers have become energetic and dynamic extension workers - sharing the technology with neighboring villages. The 'maverick project' has likewise strengthened the linkage among the NCPC-UPLB, the cooperative, the farmers, and the LGU of Asingan led by Mayor Carlos P. Reyes, Sr. and the Regional Office of the Department of Agrarian Reform (DAR). Majority of the trainees, who are beneficiaries of the DAR's Comprehensive Agrarian Reform Program (CARP), feel a strong sense of ownership over the project.

Most importantly, for Mr. Navasero, the training gas established the presence of the University in the province and earned the trust of the farmers. Throughout the training program, Ka Modesto never failed to testify about his successful experience with the SINPV and encouraged the trainees to adopt the technology. He speaks from the heart: "Technologies like the SINPV manifests the UPLB researchers' genuine and sincere desire to help poor farmers like me."

Postcript

Mr. And Mrs. Navasero have also found NPV to be effective against sasmpaguita pests Mr. Navasero is now collaborating with Drs. Pablito G. Gonzales and Rizaldo G. Bayot of the NCPC on using another NPV against tomato fruitworm (Helicoverpa armigera). Their first trials at UPLB and Majayjay, Laguna showed that applying Helicoverpa NPV twice for the whole cropping season (based on monitoring of the pest) protected the plants as adequately as the weekly spraying done by farmers. Results are being verified through field trials funded by the Department of Agriculture's Bureau of Agricultural Research (DA-BAR).